1. Field of the Invention
An aspect of the present invention relates to a wavelength selective switch.
2. Related Background Art
In recent years, a ROADM (Reconfigurable Optical Add-Drop Multiplexer) that is a light inserting and branching device in a wavelength multiplexed network has been developed according to increases in speed and capacity of communication networks. In this ROADM, a wavelength selective switch (WSS) has been developed as a device for branching or combining light. A WSS that independently controls an optical path for each wavelength component through phase modulation is disclosed in the specification of U.S. Pat. No. 7,787,720.
A WSS is described in the specification of U.S. Pat. No. 7,397,980. In this WSS, an optical signal input from an input port is spatially separated into first and second groups. The optical signals in the first and second groups are separated into wavelength components in a diffraction grating. Also, the wavelength components included in the first and second groups are incident on different areas of an LCOS SLM (Liquid Crystal On Silicon Spatial light Modulator) and deflected.